An analytical method for hafnium content in nuclear-purity zirconium alloys

Abstract

This invention relates to the field of analytical chemistry, and more particularly to an analytical method for determining the hafnium content in nuclear-grade zirconium alloys. The analytical method includes the following steps: Step S2: Dissolving a metallic or oxide hafnium isotope in concentrated hydrochloric acid and concentrated hydrofluoric acid to prepare an isotope diluent stock solution; Step S2: Adding a corresponding hafnium single-element standard solution to the isotope diluent stock solution, determining the isotope ratio R value, and calibrating the concentration of the diluent solution; Adding the calibrated isotope diluent solution to the zirconium alloy, dissolving the zirconium alloy sample in concentrated hydrochloric acid and concentrated hydrofluoric acid to obtain a sample solution to be separated; Performing extraction chromatography on the sample solution to obtain a hafnium-containing test solution; Determining the hafnium content in the hafnium-containing test solution using inductively coupled plasma mass spectrometry. This invention can accurately determine the hafnium content in nuclear-grade zirconium alloys, improving the stability and accuracy of the analytical results.

Description

Technical Field

[0001] This invention relates to the field of analytical chemistry, and in particular to an analytical method for the hafnium content in nuclear-purity zirconium alloys. Background Technology

[0002] Zirconium is a chemically stable transition metal element with a low melting and boiling point. It is also highly resistant to acids and alkalis, making it an excellent high-temperature and corrosion-resistant material. Zirconium materials also possess advantages such as radiation resistance and a small thermal neutron absorption cross-section. Zirconium and its alloys are widely used in nuclear reactor structural materials and other nuclear materials. The chemical composition of these materials directly affects the mechanical and nuclear properties of nuclear fuel elements, and even the complete operation of the nuclear reactor. Therefore, accurate and reliable determination of impurity elements in zirconium and its alloys is essential.

[0003] The main impurity element in zirconium and zirconium alloys is hafnium. Currently, the main methods for determining the hafnium content in zirconium and zirconium alloys are seed activation method, matrix matching-ICP-AES method, and matrix matching-ICP-MS method. Since zirconium and hafnium are symbiotic elements, if zirconium and hafnium are not separated, a large amount of zirconium matrix will interfere with the determination of hafnium, making the determination results unstable and inaccurate. If zirconium and hafnium are separated, hafnium will inevitably be easily lost during the separation process, resulting in inaccurate determination results. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide an analytical method for hafnium content in nuclear-purity zirconium alloys, so as to accurately determine the hafnium content in high alloys.

[0005] This invention provides a method for analyzing the hafnium content in nuclear-purity zirconium alloys, comprising the following steps:

[0006] Step S1: Take the metallic element of hafnium isotope or the oxide of hafnium isotope, add concentrated hydrochloric acid and concentrated hydrofluoric acid to dissolve it, and prepare the original solution of isotope diluent.

[0007] Step S2: Take the original isotope diluent solution, add the corresponding hafnium single-element standard solution, and determine the isotope ratio R value using MC-ICP-MS or TIMS to calibrate the concentration of the diluent solution;

[0008] Step S3: Add the calibrated isotope diluent solution to the zirconium alloy, add concentrated hydrochloric acid and concentrated hydrofluoric acid to dissolve the zirconium alloy sample, and obtain the sample solution to be separated.

[0009] Step S4: Perform extraction chromatography on the sample solution to be separated to obtain a hafnium-containing test solution;

[0010] Step S5: Determine the hafnium content in the hafnium-containing test solution using inductively coupled plasma mass spectrometry.

[0011] Preferably, in step S1, the hafnium isotope is... 179 Hf or 174 Hf.

[0012] Preferably, in step S1, the mass-to-volume ratio of hafnium isotope to concentrated hydrochloric acid is 1g:2-10mL; the mass-to-volume ratio of hafnium isotope to concentrated hydrofluoric acid is 1g:0.2-2mL.

[0013] Preferably, in step S2, the ratio of the concentration of the original isotope diluent solution to the concentration of the hafnium single-element standard solution is 1:0.8 to 1.2.

[0014] Preferably, in step S2, the concentration of the hafnium single-element standard solution is 1 μg / L.

[0015] Preferably, in step S3, the mass-to-volume ratio of the zirconium alloy to concentrated hydrochloric acid is 1g:2-10mL; the mass-to-volume ratio of the hafnium isotope to concentrated hydrofluoric acid is 1g:0.2-2mL.

[0016] Preferably, in step S4, the extraction chromatography column filled with tributyl phosphate extraction resin is used for the extraction chromatography separation, and the height of the extraction chromatography column is 8-15 cm.

[0017] The particle size of the tributyl phosphate extraction resin is 80–120 mesh.

[0018] Preferably, step S4 specifically comprises:

[0019] First, the extraction chromatography column is eluted with a mixed acid. Then, the sample solution to be separated is injected into the extraction chromatography column. Finally, hafnium is removed by elution with a mixed acid of hydrochloric acid and nitric acid to obtain the hafnium-containing test solution.

[0020] Preferably, in step S4, the mixed acid comprises 0.6–2 mol / L hydrochloric acid and 2–4 mol / L nitric acid;

[0021] The concentration of hydrochloric acid used for elution is 0.6–2 mol / L, and the concentration of nitric acid is 3–5 mol / L.

[0022] Preferably, in step S5, the measurement conditions selected for inductively coupled plasma mass spectrometry are as follows:

[0023] The radio frequency power is 1100–1300W, the carrier gas flow rate is 0.8–1.0L / min, and KED mode is used. 177 Hf is the peak determined by isotope analysis;

[0024] After the measurement is completed, the hafnium content in the zirconium alloy is calculated using the formula C = (M / Ms)·(ms / m)·(As-Bs·R) / (B·R-A), where:

[0025] As-----Abundance of the reference isotope of the element to be measured in the isotope diluent;

[0026] Bs ----- Abundance of the labeled isotope of the element to be analyzed in the isotope diluent;

[0027] A-----Natural abundance of the reference isotope of the element to be tested in the sample;

[0028] B-----Natural abundance of the labeled isotope of the element to be measured in the sample;

[0029] M-----Atomic mass of the element to be measured in the sample;

[0030] Ms----Atomic mass of the element to be measured in the isotope diluent;

[0031] ms ----- The mass of the element to be measured in the added isotope diluent;

[0032] m------Analyze sample quality.

[0033] Compared with existing technologies, the method for analyzing hafnium content in nuclear-purity zirconium alloys of the present invention combines isotope dilution with extraction chromatography and mass spectrometry, which can accurately determine the hafnium content in nuclear-purity zirconium alloys. This reduces problems such as hafnium loss during zirconium-hafnium separation and interference from the zirconium matrix during the determination process, which lead to inaccurate hafnium determination, and improves the stability and accuracy of the analysis results. Detailed Implementation

[0034] To further understand the present invention, embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the present invention.

[0035] An embodiment of the present invention discloses a method for analyzing the hafnium content in nuclear-purity zirconium alloys, comprising the following steps:

[0036] Step S1: Take the metallic element of hafnium isotope or the oxide of hafnium isotope, add concentrated hydrochloric acid and concentrated hydrofluoric acid to dissolve it, and prepare the original solution of isotope diluent.

[0037] A suitable hafnium isotope should be selected by taking into account factors such as whether it is a stable isotope, its abundance, whether other monoatomic or polyatomic elements will cause interference, and whether the isotope is easy to purchase.

[0038] Hafnium isotope preferred 179Hf or 174 Hf.

[0039] The mass-to-volume ratio of hafnium isotopes to concentrated hydrochloric acid is 1 g: 2–10 mL; the mass-to-volume ratio of hafnium isotopes to concentrated hydrofluoric acid is 1 g: 0.2–2 mL.

[0040] The original isotope diluent solution is used to prepare subsequent diluent solutions.

[0041] Step S2: Take the original isotope diluent solution, add the corresponding hafnium single-element standard solution, and determine the isotope ratio R value using MC-ICP-MS or TIMS to calibrate the concentration of the diluent solution;

[0042] The concentration of the hafnium single-element standard solution is 1 μg / L.

[0043] The concentration ratio of the original isotope diluent solution to the hafnium single-element standard solution is 1:0.8 to 1.2.

[0044] Step S3: Add the calibrated isotope diluent solution to the zirconium alloy, add concentrated hydrochloric acid and concentrated hydrofluoric acid to dissolve the zirconium alloy sample, and obtain the sample solution to be separated.

[0045] The mass-to-volume ratio of the zirconium alloy to concentrated hydrochloric acid is 1g:2-10mL; the mass-to-volume ratio of the hafnium isotope to concentrated hydrofluoric acid is 1g:0.2-2mL; preferably 1g:0.6-1.2mL.

[0046] Step S4: Perform extraction chromatography on the sample solution to be separated to obtain a hafnium-containing test solution;

[0047] Specifically:

[0048] The extraction chromatography column is first eluted with a mixed acid comprising 0.6–2 mol / L hydrochloric acid and 2–4 mol / L nitric acid; preferably, it comprises 1 mol / L hydrochloric acid and 3 mol / L nitric acid.

[0049] Extraction chromatography was performed using an extraction chromatography column packed with tributyl phosphate extraction resin, with a column height of 8–15 cm.

[0050] The particle size of the tributyl phosphate extraction resin is 80–120 mesh;

[0051] The sample solution to be separated is then injected into the extraction chromatography column, and then eluted with a mixture of hydrochloric acid and nitric acid to remove hafnium, yielding a hafnium-containing test solution.

[0052] The concentration of hydrochloric acid used for elution is 0.6–2 mol / L, preferably 1 mol / L;

[0053] The nitric acid concentration is 3–5 mol / L, preferably 4 mol / L.

[0054] Step S5: Determine the hafnium content in the hafnium-containing test solution using inductively coupled plasma mass spectrometry.

[0055] The selected measurement conditions for inductively coupled plasma mass spectrometry are as follows:

[0056] The radio frequency power is 1100–1300W, the carrier gas flow rate is 0.8–1.0L / min, and KED mode is used. 177 Hf is the peak determined by isotope analysis;

[0057] Preferably, the RF power is 1200W, the carrier gas flow rate is 0.9L / min, and KED mode is used. 177 Hf is the peak determined by isotope analysis;

[0058] After the measurement is completed, the hafnium content in the zirconium alloy is calculated using the formula C = (M / Ms)·(ms / m)·(As-Bs·R) / (B·R-A), where:

[0059] As-----Abundance of the reference isotope of the element to be measured in the isotope diluent;

[0060] Bs ----- Abundance of the labeled isotope of the element to be analyzed in the isotope diluent;

[0061] A-----Natural abundance of the reference isotope of the element to be tested in the sample;

[0062] B-----Natural abundance of the labeled isotope of the element to be measured in the sample;

[0063] M-----Atomic mass of the element to be measured in the sample;

[0064] Ms----Atomic mass of the element to be measured in the isotope diluent;

[0065] ms ----- The mass of the element to be measured in the added isotope diluent;

[0066] m------Analyze sample quality.

[0067] To further understand the present invention, the analytical method for hafnium content in nuclear-purity zirconium alloys provided by the present invention will be described in detail below with reference to embodiments. The scope of protection of the present invention is not limited by the following embodiments.

[0068] Example 1

[0069] 1. Weigh out 50 mg of hafnium dioxide solid powder ( 179In a polytetrafluoroethylene beaker, add 0.2 mL of concentrated hydrofluoric acid and 2 mL of concentrated hydrochloric acid, heat to dissolve, and dilute with water to 50 g to prepare the original isotope diluent solution.

[0070] 2. Accurately weigh 0.1 g of the original isotope diluent solution into a polytetrafluoroethylene (PTFE) beaker, add 2 mL of a mixed acid solution of 3 mol / L hydrochloric acid and 0.5 mL of concentrated hydrofluoric acid, and dilute with water to 100 g. Accurately weigh 0.5 g of the isotope diluent solution into a 50 mL PTFE beaker, accurately add 0.5 g of a 1 μg / L hafnium single-element standard solution, and determine the isotope ratio R value using the TIMS method to standardize the concentration of the diluent solution.

[0071] 3. Accurately weigh 1g of the calibrated isotope diluent solution and add it to 0.5g of zirconium alloy. Add 2mL of concentrated hydrochloric acid and 0.5mL of concentrated hydrofluoric acid to dissolve the zirconium alloy sample. Dilute with water to obtain approximately 5mL of sample solution to be separated.

[0072] 4. Pass the solution to be separated through tributyl phosphate extraction resin (resin particle size 80-120 mesh, extraction column height 8-15 cm), and rinse the column with a mixture of 1 mol / L hydrochloric acid and 3 mol / L nitric acid. At this time, zirconium reacts with the extraction resin and is adsorbed. Elute with 10 mL of a mixture of 1 mol / L hydrochloric acid and 4 mol / L nitric acid to remove hafnium, and obtain the hafnium test solution.

[0073] 5. Optimize the instrument parameters of the mass spectrometer: RF power 1200W, carrier gas flow rate 0.9L / min, KED mode. 177 Hf is the peak determined by isotope analysis.

[0074] 6. Under optimal instrument conditions, the hafnium test solution is introduced into the mass spectrometer via a peristaltic pump for isotope ratio determination.

[0075] 7. After the measurement is completed, calculate the hafnium content in the zirconium alloy. The calculation formula is C=(M / Ms)·(ms / m)·(As-Bs·R) / (B·R-A), where:

[0076] As-----Abundance of the reference isotope of the element to be measured in the isotope diluent;

[0077] Bs ----- Abundance of the labeled isotope of the element to be analyzed in the isotope diluent;

[0078] A-----Natural abundance of the reference isotope of the element to be tested in the sample;

[0079] B-----Natural abundance of the labeled isotope of the element to be measured in the sample;

[0080] M-----Atomic mass of the element to be measured in the sample;

[0081] Ms----Atomic mass of the element to be measured in the isotope diluent;

[0082] ms ----- The mass of the element to be measured in the added isotope diluent;

[0083] m------Analyze sample quality.

[0084] The hafnium in the zirconium alloy sample was determined using the above method, and the results were compared with those obtained by direct determination using conventional ICP-MS. The results are shown in Table 1.

[0085] Table 1. Determination results of hafnium in zirconium alloy samples

[0086]

[0087] As can be seen from Table 1, compared with the results of conventional ICP-MS direct measurement, the results obtained by this method are more stable, reducing the error of a single measurement and improving the stability of the measurement results.

[0088] This invention has many specific embodiments. All technical solutions that use tributyl phosphate resin separation-isotope dilution-mass spectrometry to determine the hafnium content in zirconium and zirconium alloys fall within the scope of protection claimed by this invention.

[0089] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0090] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for analyzing hafnium content in a nuclear pure zirconium alloy, characterized by, The method comprises the following steps: Step S1: taking metallic single substance of hafnium isotope or oxide of hafnium isotope, adding concentrated hydrochloric acid and concentrated hydrofluoric acid to dissolve and prepare an isotope diluent original solution; Step S2: taking the isotope diluent original solution, adding a corresponding hafnium single element standard solution, and determining the isotope ratio R value by using MC-ICP-MS or TIMS method to calibrate the concentration of the diluent solution; Step S3: adding the calibrated isotope diluent solution into a zirconium alloy, adding concentrated hydrochloric acid and concentrated hydrofluoric acid to dissolve the zirconium alloy sample to obtain a sample solution to be separated; Step S4: first, using mixed acid to elute an extraction chromatographic column, then injecting the sample solution to be separated into the extraction chromatographic column, and then using mixed acid of hydrochloric acid and nitric acid to elute hafnium to obtain a hafnium-containing solution to be measured; the extraction chromatographic column is selected to be an extraction chromatographic column filled with tributyl phosphate extraction resin, and the height of the extraction chromatographic column is 8-15 cm; The particle size of the tributyl phosphate extraction resin is 80-120 mesh; The mixed acid comprises 0.6-2 mol / L hydrochloric acid and 2-4 mol / L nitric acid; The concentration of the hydrochloric acid used for elution is 0.6-2 mol / L, and the concentration of the nitric acid is 3-5 mol / L; Step S5: determining the hafnium content in the hafnium-containing solution to be measured by using inductively coupled plasma mass spectrometry.

2. The method for analyzing hafnium content in a nuclear pure zirconium alloy according to claim 1, characterized by, In the step S1, the hafnium isotope is 179 Hf or 174 Hf.

3. The method for analyzing the content of hafnium in a nuclear pure zirconium alloy according to claim 2, characterized by, In step S1, the mass of hafnium isotope to the mass volume ratio of concentrated hydrochloric acid is 1 g:2-10 mL; and the mass of hafnium isotope to the mass volume ratio of concentrated hydrofluoric acid is 1 g:0.2-2 mL.

4. The method for analyzing hafnium content in a nuclear pure zirconium alloy according to claim 1, characterized by, In step S2, the configuration concentration of the isotope diluent original solution to the concentration of the hafnium single element standard solution is 1:0.8-1.

2.

5. The method for analyzing hafnium content in a nuclear pure zirconium alloy according to claim 4, characterized by, In step S2, the concentration of the hafnium single element standard solution is 1 μg / L.

6. The method for analyzing hafnium content in a nuclear pure zirconium alloy according to claim 1, characterized by, In step S3, the mass volume ratio of the zirconium alloy to concentrated hydrochloric acid is 1 g:2-10 mL; and the mass volume ratio of hafnium isotope to concentrated hydrofluoric acid is 1 g:0.2-2 mL.

7. The method for analyzing hafnium content in a nuclear pure zirconium alloy according to claim 1, wherein In step S5, the determination conditions of inductively coupled plasma mass spectrometry are as follows: The radio frequency power is 1100-1300 W, the carrier gas flow is 0.8-1.0 L / min, and the KED mode is adopted, 177 Hf is an isotopic determination peak; After the determination is completed, the hafnium content in the zirconium alloy is calculated, and the calculation formula is C=(M / Ms)·(ms / m)·(As-Bs·R) / (B·R-A), wherein: As is the abundance of the reference isotope of the element to be measured in the isotope diluent; Bs is the abundance of the marker isotope of the element to be measured in the isotope diluent; A is the natural abundance of the reference isotope of the element to be measured in the sample; B is the natural abundance of the marker isotope of the element to be measured in the sample; M is the atomic mass of the element to be measured in the sample; Ms is the atomic mass of the element to be measured in the isotope diluent; ms is the mass of the element to be measured in the added isotope diluent; m is the mass of the analysis sample.

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